Based on two animal bones about 3.4 million years old from an Ethiopian site, paleontologists say stone tools used by humans date back by 800,000 years earlier than previously thought.
The excavations from the town of Dikika in Ethiopia is a potential evidence for the use of stone tools, killing of large animals for food. It means the stone tools were used not since 2.6 million years ago but about 3.2 million years ago.
“Our analysis clearly shows that the marks on these bones are not characteristic of trampling,” said Jessica Thompson from Emory University.“The best match we have for the marks, using currently available data, would still be butchery with stone tools.”
The researchers found 12 marks on the two bones belonging to a creature the size of an antelope and a rib bone from an animal of the size of a buffalo with purposeful cutting and percussion marks. “When these bones were hit, they were hit with enormous force and multiple times,” explained Thompson.
The research brushed aside the objections to an original finding of a paper published in 2010 in the Nature that said the two bones had characteristics of stone tool butchery. The 2011 objection said it could have been due to incidental trampling in abrasive sediments.
Thompson and her team examined the surfaces of a sample of more than 4,000 other bones from the same deposits and then used statistical methods to compare more than 450 marks found on those bones to experimental trampling marks and to the marks on the two controversial specimens.
“We would really like to understand what caused these marks,” Thompson says. “One of the most important questions in human evolution is when did we start eating meat, since meat is considered a likely explanation for how we fed the evolution of our big brains.”
Evidence shows that our genus, Homo, emerged around 2.8 million years ago with changers in his brain size that indicates higher quality diet, which means he began to kill animals bigger in size than him.
In addition to Dikika, other recent finds are uprooting the long held views of hominin evolution and when human behaviors emerged. This year, a team led by archeologist Sonia Harmand in Kenya reported unearthing stone tools that have been reliably dated to 3.3 million years ago, or 700,000 years older than the previous record.
“We know that simple stone tools are not unique to humans,” Thompson says. “The making of more complex tools, designed for more complex uses, may be uniquely human.”